JPH02107270A - Gasket and medical instrument using the same - Google Patents

Abstract

PURPOSE:To provide a gasket excellent in moldability and elution safety and generating no pulsation phenomenon and a medical instrument using the same by forming the gasket from a composition consisting of a hydrogenated derivative of a styrene/butadiene block copolymer, a rubber softener and a polyester type elastomer. CONSTITUTION:This gasket 5 is formed from a composition consisting of an a-component being a hydrogenated derivative of a styrene/butadiene block copolymer, a b-component being a rubber softener and a c-component being a polyester type elastomer. In this composition for the gasket 5, 20-150 pts.wt. of the c-component is compounded per 100 pts.wt. of the sum amount of 30-70wt.% of the a-component and 70-30wt.% of the d-component. By adding the polyester type elastomer in place of polypropylene constituting conventional styrenic thermoplastic elastomer, the hydrogenated derivative of the styrene/ butadiene block copolymer does not lose the original rubbery elasticity and can secure moldability and elution safety. By this method, the gasket excellent in moldability an elution safety and generating no pulsation phenomenon is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a gasket and a medical instrument using the same.

[Prior Art] Some medical instruments, such as disposable syringes, include a cylindrical body and a gasket that slides in close contact with the inner wall surface of the cylindrical body.

Conventionally, the gasket has been made of vulcanized rubber or a styrene-based thermoplastic elastomer (hereinafter abbreviated as TPE), as described in Japanese Patent Publication No. 59-18427. Styrenic TPE is a composition consisting of a hydrogenated derivative of a styrene-butadiene block copolymer, a rubber softener, and polypropylene for adjusting processability and hardness.

[Problem 111 to be solved by the invention] However, gaskets made of vulcanized rubber require large-scale equipment because they undergo a complicated vulcanization process. Additionally, many additives such as sulfur, vulcanization accelerators, fillers, etc. are required, and as a result, these additives may be leached into the liquid during use of the medical device.

On the other hand, gaskets made of styrene TPE
Although it is excellent in moldability by injection molding and safety due to no elution of sulfur, etc., it is inferior in rubber elasticity compared to vulcanized rubber. Here, "rubber elasticity" means that especially in tensile properties, inflection points such as yield points are as small as possible, and the modulus (for example, stress at 300% elongation) is high in relation to hardness. That is, styrenic TP
In H, polypropylene, which is a component thereof, causes an inflection point such as a yield point in rubber elasticity, particularly in tensile properties, and causes a decrease in modulus. For this reason, when a gasket made of styrene-based TPE is used, for example, in a syringe, the displacement applied to the pusher does not immediately translate into the amount of gasket movement, causing the gasket to move intermittently, a so-called pulsation phenomenon. There is an inconvenience.

An object of the present invention is to provide a gasket that has excellent moldability and elution safety and does not cause pulsation, and a medical instrument using the same.

[Means for Solving the Problem] The gasket according to claim 1 comprises a hydrogenated derivative of styrene Φ butadiene block copolymer (component a), a rubber softener (component b), and a polyester elastomer (component b).
It is made of a composition consisting of component a).

In the gasket according to claim 2, the composition includes a total amount of 30 to 70% by weight of component a and 70 to 30% by weight of component b.
00 parts by weight, 20 to 150 parts by weight of component C is blended.

The medical instrument according to claim 3 is a medical instrument comprising a cylindrical body and a gasket that slides in close contact with the wall surface of the cylindrical body, the gasket according to claim 1 or 2.
It is made up of the following.

[Function] The components and blending ratio of the composition constituting the gasket of the present invention will be described in detail below.

The above component a used in the present invention has the general formula %) [where A is a monovinyl-substituted aromatic hydrocarbon polymer block, and B is a conjugated diene elastomeric polymer block. and n is an integer of 1 to 5] is a hydrogenated derivative of a block copolymer.

Although various monovinyl-substituted aromatic hydrocarbon monomers constituting the polymer block A may be used, styrene and α-methylstyrene are particularly preferred. The conjugated diene monomer of polymer blow 2 B in the same formula is preferably butadiene or isoprene, and a mixture of both may be used. When forming the combined block B, ! in the microstructure of the polybutadiene is used for the purpose of retaining elastomeric properties. , 2 - Microstructure is 20-50
It is preferable to adopt polymerization conditions such that 1,
2- A microstructure of 35-45% is suitable. The proportion of one polymer block B in the copolymer is preferably at least 65% by weight.

The average molecular weight of the polymer block A is 5.000 to 12
5.000, Block B is 15,000-250,0
It is preferably in the range of 00.

The block copolymer used in the present invention is hydrogenated.

Many methods have been proposed as methods for producing hydrogenated derivatives of block copolymers having the above-mentioned general formula.
There is a method described in publications such as No. 43-883111.

In the hydrogenation during its production, at least 50%, preferably 80% or more of the olefinic double bonds in polymer block B are hydrogenated, and 25% or less of the aromatic unsaturated bonds in one polymer block A are hydrogenated. is preferably hydrogenated. As such a block polymer, a commercially available polymer such as KRA-0N-G (trade name manufactured by Shell Chemical Co., Ltd.) can be used.

As the rubber softener of the above-mentioned components used in the present invention, mineral oil-based or synthetic resin-based softeners are suitable.

Mineral oil-based softeners are a combination mixture of aromatic rings, naphthenic rings, and paraffin chains, and those in which the number of carbon atoms in the paraffin chain accounts for 50% or more of the total carbon are called paraffinic softeners. Those containing 30 to 45% of aromatic carbons are called naphthenic, and those containing more than 30% aromatic carbon are called aromatic. Among these, mineral oil-based softeners preferable as component b of the present invention are naphthenic and paraffinic softeners, and aromatic hydrocarbons contain 3
0% or less. Aromatic systems are used in the present invention.
It is not very preferable in terms of dispersibility with respect to component (a).

The properties of the mineral oil softener are as follows: viscosity at 37.8°C is 2.
0 to 500 cst, a pour point of -10 to -15°C, and a flash point (00G) of 170 to 300°C are used.

As the synthetic resin softener, polybutene, low molecular weight polybutadiene, etc. can be used, but mineral oil softeners are preferred.

L imaginary j The C component polyester elastomer used in the present invention is as follows.

■Block copolymer consisting of aromatic polyester block (a) and non-aromatic polyester block (b) ■Block copolymer consisting of aromatic polyester block (a) and polyether block (a) ■Aromatic polyester There are block copolymers consisting of block (a) and the above-mentioned (b) and (a).

The aromatic polyester block (a) is a polyester oligomer having a structure in which an aromatic dicarboxylic acid and a diol are condensed, and examples thereof include polyethylene terephthalate oligomer, polypropylene terephthalate oligomer, polytetramethylene terephthalate oligomer, polypentamethylene terephthalate oligomer, etc. .

The non-aromatic polyester block (b) is (1) a polyester oligomer in which an aliphatic or alicyclic dicarboxylic acid is condensed with an aliphatic diol (2) a polyester synthesized from an aliphatic lactone or an aliphatic monool carboxylic acid. Examples of the former (1) include alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, dicyclohexyl-4,4°-dicarboxylic acid, succinic acid, and oxalic acid. ,
Examples include polyester oligomers having a structure in which one or more aliphatic dicarboxylic acids such as adipic acid and sebacic acid are condensed with one or more diols such as ethylene glycol, propylene glycol, tetramethylene glycol, and pentamethylene glycol. Examples of the latter (2) include polycaprolactone-based polyester oligomers synthesized from ε-caprolactone, ω-oxycaproic acid, and the like.

The polyether block (a) is 1, for example, poly(
The average molecular weight of alkylene oxide) glycol, etc. is approximately 4
00 to 8,000 polyether oligomers.

Poly(alkylene oxide) glycols include polyethylene glycol, poly(1,2 and 1,3 propylene oxide) glycol, poly(tetramethylene oxide) glycol, poly(hexamethylene oxide) glycol, block or random ethylene oxide and propylene oxide Examples include copolymers, block or random copolymers of ethylene oxide and tetrahydrofuran, and the like.

The polyester elastomer (component a) may be produced by first synthesizing the oligomer blocks consisting of the component and then condensing the blocks through ester bonds, or as another method, For example, a method may be used in which block (b) is first polymerized and then further mixed with the component monomers of block (a) and condensed.

As such a polyester elastomer, commercially available polymers such as Pelprene P and S (trade name manufactured by Toyobo Co., Ltd.) and Hytrel (trade name manufactured by Toshi DuPont Co., Ltd.) can be used.

Thermoplastic elastomers based on hydrogenated derivatives of styrene-butadiene block copolymers usually contain a rubber softener and a resin component (e.g. polypropylene) for the purpose of adjusting hardness and processability. However, the present invention is characterized in that a certain amount of polyester elastomer is added as this resin component.

That is, it was conventionally thought that a thermoplastic elastomer having heat resistance and rubber elasticity could be obtained by using polypropylene resin. However, the present inventors have discovered that by using a polyester elastomer in place of the polypropylene resin, the rubber elasticity and heat resistance of the material can be improved.

The blending ratio of components a, b, and c in the plastic elastomer of the present invention is such that component a is 30 to 70% by weight, preferably 35 to 70% by weight.
It is 60% by weight. If it is less than 30% by weight, the rubber elasticity and heat resistance of the thermoplastic elastomer obtained will be poor;
If it exceeds this, flexibility and moldability will deteriorate.

Component b is 70 to 30% by weight, preferably 85 to 40% by weight.
It is. If it exceeds 70% by weight, rubber elasticity and heat resistance will be poor, and if it is less than 30% by weight, flexibility and moldability will deteriorate.

Component C is 20 parts by weight per 100 parts by weight of components a and b.
-150 parts by weight, preferably 30-100 parts by weight. If it is less than 20 parts by weight, moldability is poor.150 parts by weight
If it exceeds this, flexibility will be lost.

The present invention is characterized by containing a predetermined amount of these essential components when obtaining a thermoplastic elastomer. 1. Polyolefin polymers, polystyrene polymers, etc., calcium carbonate, Inorganic fillers such as talc, calica, and carbon black can be added. In addition, antioxidants, ultraviolet absorbers, slip agents, and fluidity improvers (
Additives such as polyethylene resin (X, etc.) can be added.

The method for producing the thermoplastic elastomer of the present invention can be by mechanical melt mixing. Specifically, general melt mixers such as Banbury mixer 5 various kneaders 1 single-screw or twin-screw extruders can be used.

Further, the thermoplastic elastomer of the present invention can be molded by thermoplastic resin molding methods such as injection molding, extrusion molding, and blow molding.

That is, the TPE forming the gasket of the present invention is a hydrogenated derivative of a styrene-butadiene block copolymer by adding a polyester elastomer instead of the polypropylene that constitutes the conventional styrene TPE mentioned above. It is possible to ensure moldability and elution safety without impairing the inherent rubber elasticity. This results in
It is possible to obtain a gasket that has excellent moldability and elution safety and does not cause a pulsation phenomenon, and a medical device using the same.

[Example] Fig. 1 is a schematic diagram showing a syringe to which the gasket of the present invention is applied, and Fig. 2 is a diagram showing the results of a pulsation test.

In the injection machine 10 shown in FIG. 1, 1 is a syringe made of hard synthetic resin, 2 is a nozzle, and 3 is a flange. 4 is a pusher made of hard synthetic resin, and 5 is a gasket of the present invention fitted into the end engagement portion 4A of the pusher 4.

In the following Examples and Comparative Examples, the test methods used for various evaluations are as shown below.

All measurement samples were injected using a 5-ounce in-line screw type injection molding machine at an injection pressure of 500 kg/cm.
2. Injection temperature: 22Q"O1 Mold temperature: 40'O-t' Molded 2cm thick sheet (sample for test items (1) and (2) below) and gasket for 5-gram syringe with peak diameter of 13.2+u+ (Samples for the following test items (3) to (5)) were obtained.The inner diameter of the outer cylinder for the five-intestinal syringe was 13.0 mm.

(1) JIS-A hardness: In JISK-6301 syringe gaskets, if it is too hard, sliding and assembling properties will be poor, and if it is too soft, the engagement force with the pusher will be insufficient, resulting in disconnection. . The appropriate hardness is 20 or more and 85 or less.

(2) 300% stress (kg/cs+2)...JI
In relation to SK-f1301 hardness, this 300%
The higher the stress, the less likely pulsation will occur; when the hardness is about 68-65, pulsation will occur if the 300% stress is 22-25 kg/cm2 or less.

(3) Formability Evaluation was made based on flowability during injection molding.

(4) Using a syringe pump 20 as shown in FIG. 2 that pushes a pusher inserted into a pulsating syringe at a constant speed, set the syringe l that has sucked wood into the syringe pump 20, and press the syringe pump 20. The syringe discharge amount by the child head 21 is set to 1
I set it to intestinal sentence/time. At this time, the amount of water discharged from the syringe 1 is detected by the detector 22 as a droplet of approximately 1/60 volume, and this detection result is recorded by the recording device 24 via the amplifier 23, and the signal line shown in FIG. I got the diagram. If the signal intervals in FIG. 2 are constant, the discharge amount per unit time is constant, which means that there is no pulsation.

(5) The degree of elution of the oil bleed rubber softener was evaluated by visually observing changes in the state of the gasket surface at a temperature of 23° C. and after 7 days of use.

Further, each compounding component used in the Examples and Comparative Examples is as follows.

(a) Hydrogenated derivative of styrene-butadiene block copolymer...R KRA-0N- manufactured by Shell Chemical Co., Ltd.
G1851 J (Blue 2K field viscosity: 20
2000 cps in wt% toluene solution, 77°F) (b
) Rubber softener: Liquid paraffin manufactured by Idemitsu Kosan Co., Ltd.
P1380 J (40℃ kinematic viscosity: 381.8cs
t) (c-1) Polyester elastomer...Toyobo Pelprene (polyester ether elastomer) P
-708 (JIS-A code 138 [-], crystal melting point 2
00 [℃] ) (c-2) Polyester elastomer...P-30
8 (JIS-A code 70[-], crystal melting point lθ0[
"C]) (c-3) Polyester elastomer...
Toyobo Pelprene (polyester ether elastomer) P-150B (JIS-A code 9B [-], crystal melting point 212 [°C]) (c-4) Polypropylene resin for comparative example... "Mitsubishi Polypro BC5CJ (NFR: 5 g/10 ) Examples 1 to 3 and Comparative Example 4 To the various formulations shown in Table 1, 1 part by weight of the phenolic antioxidant "Irganox IOJ O," was added as a stabilizer to 100 parts by weight of this formulation, L/D
-33, by a two-wheel extruder with a cylinder diameter of 45 layers,
TPE pellets were obtained by melt-kneading at a set temperature of 220°C.

Using this pellet, the thickness is 2 by injection molding as described above.
A sheet for evaluation with 1 win and a gasket for evaluation with a peak diameter of 13.2 mm were molded. Table 1 shows the results of various evaluations performed on the obtained sheets and gaskets.

The gaskets of Examples 1 to 3 are gaskets according to claim 1.2, and have high stress at equivalent hardness, good rubber elasticity, and good moldability, pulsation, and oil bleeding.

[Effects of the Invention] As described above, according to the present invention, it is possible to obtain a gasket that has excellent moldability and elution safety and does not cause a pulsation phenomenon, and a medical instrument using the same.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a syringe to which the gasket of the present invention is applied, and FIG. 2 is a diagram showing the results of a pulsation test. 1...Syringe, 5...Gasket, 10...Syringe.

Claims (3)

[Claims] (1) A gasket formed from a composition consisting of a hydrogenated derivative of a styrene-butadiene block copolymer (component a), a rubber softener (component b), and a polyester elastomer (component c). (2) The composition comprises 20 to 150 parts by weight of component c to 100 parts by weight of a total of 30 to 70% by weight of component a and 70 to 30% by weight of component b. Gasket as described. (3) A medical device comprising a cylindrical body and a gasket that slides in close contact with the wall surface of the cylindrical body, wherein the gasket is the one according to claim 1 or 2. utensils.